Detoxifying mycotoxins in poultry feed

THE POULTRY SECTOR of sub-Saharan Africa’s agriculture is essential to the economic impact the industry has on the overall regional economy. However, the sector is faced with feed insecurity and feed safety in the wake of mycotoxin contaminations within the livestock feed.

Mycotoxins are toxic compounds which naturally produce certain types of fungi in numerous types of food supplies. The mycotoxins are chemically stable and can occur before or after harvest and during storage, where they grow on or within the feed under humid conditions. Among the most poisonous of the mycotoxins are the aflatoxins (AFs) – the most present mycotoxin in the Tropics – which grow in soil, decaying vegetation, hay and grains, as well as in the milk of animals which have eaten the contaminated feed.

Affected poultry products

Large doses of the toxins can be detrimental to not only poultry health, but to humans as well. Increased exposure to contaminated feed can lead to life-threatening acute poisoning (aflatoxicosis) of the liver, as well as potentially damaging livestock DNA and causing cancer. The toxins also have an effect on the bird performance by reducing egg production numbers, thus enhancing economic losses across the industry.

Mycotoxins also bestow immunosuppressive effects onto the birds and have been shown to reduce disease resistance as well as reduce drug efficiency, leading to the birds becoming more susceptible to different types of diseases, as well as accelerating mortality numbers.

Relating back to the economic losses the industry is facing in wake the of mycotoxin outbreaks, farmers are having to incur costs associated with treatment for their livestock, as well as the overall loss that comes with higher mortalities. Stunted growth can be attributed to contaminated feeds also, resulting in more money having to be spent on increased feed to attain the poultry desired weight, as well as valuable time lost trying to catch that weight up.

Looking at the effects mycotoxins can have on humans, feeding the contaminated grains to the birds can lead to the retention of aflatoxins in the poultry tissue, which can constitute to a major public health risk when humans consume any of the poultry products, including meat, eggs and liver. There is evidence to suggest that prolonged exposure to large doses of mycotoxins can cause serious issues harm to humans, including, in the most serious instances, liver cancer.

Tropical countries, including Nigeria, Ghana, Kenya and Uganda, have experienced AF levels in feed products well above the EU regulatory limit of 20 µg/kg. The main source of high AF occurrences is within oilseeds, especially peanut and sunflower. According to the Toxins journal, Benin, Cameroon, Ethiopia and Nigeria reported more than 60% of peanuts had high levels of AFs of up to 11,900 µg/kg, and in Malawi, Uganda and Ethiopia, all maize samples recorded were contaminated with AFs at the maximum level of 150 µg/kg.

Outbreaks in feed, like the aforementioned maize, has reportedly been the cause of death for large numbers of poultry across Kenya and Morocco, with three different outbreaks having occurred in Kenya on separate occasions.

Detoxifying the toxins

In an effort to detoxify poultry feeds contaminated by aflatoxins and prevent outbreaks, a study conducted in the Journal of Applied Poultry Research tested the effects of activated charcoal, bentonite and fuller’s earth. These absorbents prove more cost effective than the likes of mycofix, aluminosilicates and esterified glucomannan; all of which have successfully bound mycotoxins and stopped them from absorbing into the poultry’s digestive system, however, they are inaccessible to economically-challenged farmers.

Utilising locally available absorbents is imperative in combating the outbreaks relating to mycotoxins. The study found that out of the three locally produced absorbents, bentonite proved most effective in preventing diseases related to toxin-absorption within the poultry tissue, compared to activated charcoal and fuller’s earth. In countries like Nigeria, Kenya and Tanzania, the Toxins journal states that one of the most prominantly used absorbents used is that of commercial clay-based mycotoxin binders, which have been imported by feed processors for use in the feed formulas. However, there is little evidence to monitor the safety and efficiency of these methods, in SSA countries, but the commercial binders have proven to protect broiler chickens from the toxic effects.

Other options to limiting the high contraction of mycotoxins is to dry cereal products prior to storage to reduce the high humidity factor the toxins mutate in, and introducing certain types of bacteria into the feed which consume mycotoxins in the gut of the poultry. h